Characterization of Flavonoid 7-O-Glucosyltransferase from Arabidopsis thaliana
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Most flavonoids found in plants exist as glycosides, and glycosylation status has a wide range of effects on flavonoid solubility, stability, and bioavailability. Glycosylation of flavonoids is mediated by Family 1 glycosyltransferases (UGTs), which use UDP-sugars, such as UDP-glucose, as the glycosyl donor. <I>AtGT-2</I>, a UGT from <I>Arabidopsis thaliana</I>, was cloned and expressed in <I>Escherichia coli</I> as a gluthatione <I>S</I>-transferase fusion protein. Several compounds, including flavonoids, were tested as potential substrates. HPLC analysis of the reaction products indicated that AtGT-2 transfers a glucose molecule into several different kinds of flavonoids, eriodictyol being the most effective substrate, followed by luteolin, kaempferol, and quercetin. Based on comparison of HPLC retention times with authentic flavonoid 7-<I>O</I>-glucosides and nuclear magnetic resonance spectroscopy, the glycosylation position in the reacted flavonoids was determined to be the C-7 hydroxyl group. These results indicate that <I>AtGT-2</I> encodes a flavonoid 7-<I>O</I>-glucosyltransferase.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(6), 1471-1477, 2006-06-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry